Metal-matrix composite (MMC) materials are useful in a variety of industries. Generally, MMCs are comprised of a variety of ceramic materials contained in a metal matrix. The ceramic materials are usually in the form of particles or continuous fibers. Particulate MMCs are reinforced with ceramic particles. One such MMC of interest is silicon carbide/aluminum (SiC/Al) MMC. SiC/Al MMCs are candidate packaging materials for electronic components. Low density and a coefficient of thermal expansion relatively close to that of gallium arsenide make SiC/Al MMCs attractive for electronic component packaging. Moreover, silicon carbide/aluminum is a favored particulate metal-matrix composite where superior attributes such as hardness and stiffness, strength at elevated temperatures, high thermal conductivity, low coefficient of thermal expansion and resistance to wear and abrasion are of primary value.
Unfortunately, the properties that make MMCs attractive also render them difficult to fabricate, and very difficult if not impossible to machine by conventional cutting methods (i.e., diamond edge tools) since the particles dull and abrade cutting tools. For example, when forming an electronic package, typically a network of channels and cavities are machined into the packing material in which the electronic components are to be mounted. SiC/Al MMCs are difficult to machine using conventional cutting methods since the hard SiC reinforcement particles abrade and dull the cutting tools. MMCs having high silicon carbide content cannot be effectively machined using conventional physical machining techniques.
Currently, particulate MMCs, including SiC/Al MMCs in particular, have been machined by conventional cutting methods with limited success. Excessive tool wear and subsurface damage to the work piece have prevented the cutting method from being widely accepted. In the case of MMCs with high SiC particle volume fraction, components cannot be machined and must be cast to near net shapes. Casting can be very expensive for small lot sizes and can limit the variety of parts to be fabricated. Additionally, powder metallurgy and hot-pressing techniques have been employed to produce MMCs; however, only relatively simple shapes can be formed by these methods. This difficultly in fabrication has severely limited the use of MMCs. Thus, the development of alternative machining methods for MMCs is desired and would be a significant advance in the art.